Systems are known for the counting of red and white blood cells wherein a transducer is employed having a pair of electrodes disposed within a fluid path and with an aperture therebetween through which a blood sample is caused to flow. The impedance of the fluid path as sensed by the electrodes is materially altered by the presence of a blood cell within the aperture giving rise to electrical pulses which are electrically counted and which correspond to the number of blood cells passing through the aperture. Such systems employ means for metering a known volume of cell containing liquid, such that a cell count for a known volume of liquid can be provided. A preferred blood cell counting system is shown in U.S. Pat. No. 3,657,725, assigned to the assignee of this invention.
There is a need for blood cell counting systems which are automatic in operation so that relatively untrained personnel may be employed for system operation and so that less time is required for attendance to system operation even with trained personnel.